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Original version

Abstract

W and Z bosons are massive weakly-interacting particles, insensitive to the strong interaction. They provide therefore a medium-blind probe of the initial state of the heavy-ion collisions. The final results for the W and Z-boson production in p–Pb collisions at √sNN = 5.02 TeV are presented. The production cross-section is well described by perturbative calculations but the data cannot further constrain the nuclear modification of the parton distribution functions. The Wboson production is also studied as a function of the collision centrality, and found to be constant within uncertainties. The Z-boson production was also measured in Pb–Pb collisions at √sNN = 5.02 TeV with ALICE. This is the first measurement at forward rapidity at such energies. The preliminary results for the invariant yields divided by the nuclear overlap functions are described by perturbative calculations including nuclear modifications of the PDFs.